Cryosurgical probe with adjustable freeze zone

ABSTRACT

A cryosurgical probe includes an actuator housing assembly and an actuator assembly. The actuator housing assembly includes an actuator housing having an elongated central opening therethrough. The actuator housing has a proximal end portion and a distal end portion. A delivery system for a cryogenic fluid, includes a first end secured to the proximal end portion of the actuator housing. An insulation layer has a proximal portion securely attached to the proximal end portion of the actuator housing. An actuator assembly includes a rotatable actuator having a portion thereof contained within the actuator housing. The rotatable actuator is rotatable relative to the actuator housing. A cryosurgical shaft assembly is securely attached to the rotatable actuator. The insulation layer extends along an inner surface of the cryosurgical shaft to define insulated portions of the cryosurgical shaft and uninsulated portions. The relative disposition of insulated and uninsulated portions of the cryosurgical shaft assembly defines at least one freeze zone, which is adjustable by relative rotation between the rotatable actuator and the actuator housing.

CROSS REFERENCE TO RELATED APPLICATIONS

[0001] This application is a continuation-in-part of U.S. Ser. No. 09/957,337 filed Sep. 20, 2001.

BACKGROUND OF THE INVENTION

[0002] 1. Field of the Invention

[0003] The present invention relates to cryosurgical probes and more particularly to a cryosurgical probe that provides an adjustable freeze zone.

[0004] 2. Description of the Related Art

[0005] Conventional cryosurgical probes generally have the probe tip permanently affixed to a probe instrument body, including a handle member, for example. Other probes were invented long ago which involved the use of removable and interchangeable probe tips, for example, U.S. Pat. No. 4,211,231, entitled “Cryosurgical Instrument”, issued to R. P. Rzasa. In the surgical destruction of tumors by freezing, different size probe tips may be required to treat different sizes and shapes of tumors. However, it is not generally practical or feasible to design or have available probe tips which have the ideal or optimum freezing area/length for every conceivable type of tumor. Therefore, there have been some proposals in the prior art to provide cryosurgical probe devices with means for adjusting the freezing zone by manipulating the length or penetration of the coolant delivery and/or coolant line with respect to the expansion chamber of the probe tip.

[0006] U.S. Pat. No. 3,398,738, entitled “Refrigerated Surgical Probe,” issued to B. L. Lamb et al, discloses a cryosurgical probe in which the opening of its liquid refrigerant delivery tube may be longitudinally or axially adjustable. This manipulates the rate of flow of refrigerant. It does not change the freeze zone.

[0007] U.S. Pat. No. 4,015,606 to Mitchiner, et al. discloses a cryosurgical probe having a cooling chamber that is permanently separated from the insulating chamber in which a supply conduit extends into the cooling chamber of the probe tip, wherein the freeze zone in the cooling chamber is controlled by adjusting the position of the refrigerant exhaust conduit in the tip relative to the position of the supply conduit. However, only minor, if any, adjustment is available with this device. Furthermore, the problems inherent in permanent vacuum seals still exist.

[0008] U.S. Pat. No. 6,551,274, entitled “Cryoablation Catheter With An Expandable Cooling Chamber” discloses a cryoablation catheter having an expandable cooling chamber in which the cooling fluid, preferably a gas, serves to expand the expandable cooling chamber while simultaneously cooling the chamber. The cryoablation catheter includes an outer tubular member capable of insertion into the vessels of the body. An expandable cooling chamber, which preferably takes the form of a distendable balloon, is disposed at the distal end of the outer tubular member. An inner tubular member is disposed within the outer tubular member and extends through a passageway in the wall of the outer tubular member. The inner tubular member serves to carry a cooling fluid to the interior of the expandable cooling chamber. A fluid expansion nozzle is disposed on the distal end of the inner tubular member. Preferably the fluid expansion nozzle takes the form of a Joule-Thomson nozzle. By applying a cooling fluid to the inner tubular member it is possible to expand the expandable cooling chamber while simultaneously cooling the chamber.

[0009] U.S. Pat. Nos. 6,547,785 and 6,497,703, each entitled “Cryoablation Catheter For Long Lesion Ablations,” each disclose a cryoablation catheter, comprising an outer tubular body with a closed distal end to form a fluid cooling chamber and an inner tubular member having a proximal end adapted to receive fluid suitable for cryoablation and a distal end coupled to a fluid expansion nozzle wherein the inner tubular member is movable in an axial direction to thereby change the position of the nozzle within the fluid cooling chamber.

[0010] The '703 patent discloses the concept of “dragging” the ablation tip, or the cooling tip, of a cryoablation catheter along a line in order to create a long lesion. In order to accomplish this function, the cryogenic cooling nozzle is moved longitudinally along the inside of a cooling chamber to thereby cause the outer surface of the cooling chamber to be cooled along a linear path which in turn creates a linear lesion along the path.

[0011] The '785 patent emphasizes that the catheter system includes a nozzle control system which is comprised of an inner ring member formed of a magnetic material which is mounted on the proximal end of the inner tubular member, and an outer ring member formed of magnetic material which is slidably mounted on the outer tubular member. Because of the magnetic attraction between these two magnetic members, when an outer ring member is moved along the outer tubular member it “pulls” or draws an inner magnetic ring member along with the outer magnetic ring member to thereby cause the inner tubular member to be moved longitudinally which in turn causes the fluid expansion nozzle to be moved longitudinally within the cooling chamber.

[0012] Both of these patents involve changing the location of the freeze zone but do not increase or increase the length of the freeze zone.

SUMMARY OF THE INVENTION

[0013] In one broad aspect, the present invention is embodied as a cryosurgical probe for providing an adjustable freeze zone. The cryosurgical probe includes an actuator housing assembly and an actuator assembly. The actuator housing assembly includes an actuator housing having an elongated central opening therethrough. The actuator housing has a proximal end portion and a distal end portion. A delivery system for a cryogenic fluid, includes a first end secured to the proximal end portion of the actuator housing. An insulation layer has a proximal portion securely attached to the proximal end portion of the actuator housing.

[0014] An actuator assembly includes a rotatable actuator having a portion thereof contained within the actuator housing. The rotatable actuator is rotatable relative to the actuator housing. A cryosurgical shaft assembly is securely attached to the rotatable actuator. The insulation layer extends along an inner surface of the cryosurgical shaft to define insulated portions of the cryosurgical shaft and uninsulated portions. The relative disposition of insulated and uninsulated portions of the cryosurgical shaft assembly defines at least one freeze zone which is adjustable by relative rotation between the rotatable actuator and the actuator housing.

[0015] In one preferred embodiment the rotatable actuator is operatively engaged with the actuator housing to provide axial movement therebetween during rotation of the rotatable actuator thereby changing the length of the freeze zone.

[0016] In another preferred embodiment, instead of changing the length of the freeze zone, rotation of the actuator housing relative to the rotatable actuator changes the position of insulation located on a selected portion of the cryosurgical shaft assembly and effects an adjustment in the freeze zone.

BRIEF DESCRIPTION OF THE DRAWINGS

[0017]FIG. 1 is a cross sectional view, partially in cross section, of a first embodiment of the cryosurgical probe of the present invention in which the freezing zone can adjusted to be longer or shorter.

[0018]FIG. 2 is another cross sectional view of the FIG. 1 embodiment, showing the shaft assembly detracted relative to the insulation, illustrating how the freeze zone length is decreased.

[0019]FIG. 3 is a cross sectional view, partially in cross section, of the cryosurgical probe, including its fluid supply line.

[0020]FIG. 4 is a cross sectional view of another embodiment in which the cryosurgical probe is angled.

[0021]FIG. 5 is a cross sectional view, partially in cross section of another embodiment in which there is no longitudinal relative movement of the cryosurgical shaft assembly relative to the actuator housing, and instead, insulation is located on a selected portion of the cryosurgical shaft assembly so that rotation effects a change in the freeze zone.

[0022]FIG. 6 is a view taken along line 6-6 of FIG. 5.

[0023]FIG. 7 is a cross sectional view, partially in cross section, of another embodiment of the cryosurgical probe of the present invention in which the actuator housing and the actuator are reversed.

[0024]FIG. 8 is another cross sectional view of the FIG. 8 embodiment, showing the shaft assembly detracted relative to the insulation, illustrating how the freeze zone length is decreased.

DETAILED DESCRIPTION OF THE INVENTION

[0025] Referring now to the drawings and the characters of reference marked thereon, FIGS. 1 and 2 illustrate a preferred embodiment of the cryosurgical probe of the present invention, designated generally as 10. The cryosurgical probe 10 includes an actuator housing assembly (i.e. stationary assembly), designated generally as 12, and an actuator assembly (i.e. positionable assembly), designated generally as 13. The stationary assembly 12 includes an actuator housing 14 having an elongated central opening therethrough. The actuator housing 14 has a proximal end portion 16 and a distal end portion 18. The actuator housing is preferably formed of a hard metal such as stainless steel.

[0026] A cryostat assembly 20 includes a cryostat housing 22. The cryostat housing 22 includes a cryostat housing attachment end 24 secured to the proximal end portion 16 of the actuator housing 14. The cryostat assembly 20 also includes a cryostat 26 that comprises a coiled heat exchanger. A cryostat inlet receives gas entering the cryostat while a cryostat outlet provides the gas to the Joule-Thomson nozzle, as will be explained below. The coiled heat exchanger is coiled around a mandrel. In between each winding of the heat exchanger, gaps are formed between the coil and the main body portion, and gaps are formed between the coil and the mandrel. This construction is known as a Giaque-Hampson heat exchanger. The heat exchanger, which is an integral part of the high pressure gas pathway, is made with finned tubing, with numerous fins throughout its length.

[0027] A stationary cylindrical insulation layer 28 has a proximal portion 30 securely attached to a proximal end portion 16 of the actuator housing 14 through a spacer 32. The insulation layer 28 may be, for example, a vacuum, a space or it may formed of an insulation material such as Teflon® or glass fiber.

[0028] A Joule-Thomson tube assembly 34 is securely positioned within the actuator housing 14. The Joule-Thomson tube assembly 34 may be formed of, for example, stainless steel.

[0029] The positionable assembly 13 of the cryosurgical probe 10 includes a rotatable cylindrical actuator 36 having a portion thereof contained within the actuator housing 14. The cylindrical actuator 36 is rotatable relative to the actuator housing 14, preferably through the use of threads 38. A cryosurgical shaft assembly 40 is securely attached to the rotatable cylindrical actuator 36 so that that there is no relative rotation therebetween. The cryosurgical shaft assembly 40 includes an outer sheath that is preferably formed of stainless steel.

[0030] In the embodiment shown in FIGS. 1 and 2 the threads 38 are utilized to provide the required rotation of the cylindrical actuator 36 relative to the actuator housing 14. Therefore, as can be seen in FIG. 2, during operation, as the cylindrical actuator 36 is rotated relative to the actuator housing 14 so that it moves longitudinally inwardly, the Joule-Thomson tube assembly remains stationary but the cryosurgical probe tip 41 moves longitudinally inwardly. Thus, the boiling chamber length deceases from L1 to L2, where L2=L1−DX, where DX is the distance that positionable assembly 13 is detracted. This provides a commensurate decrease in the freeze zone length. The boiling chamber length, L, is shown as the distance from the end of the insulation layer 28 to the end of the expansion chamber 42 that contains the discharging gas.

[0031] Referring now to FIG. 3, the remainder of the cryosurgical probe is shown including a fluid supply line assembly including a the high pressure fluid supply line 44 surrounded by a flexible hose 46 which terminates with a high pressure connector 47. A temperature measurement device, i.e. a thermocouple 48, is positioned within the elongated shaft assembly, extends through the fluid supply line assembly and is connectable to a data acquisition system. The thermocouple 48 is used to measure and monitor the temperature inside the cryosurgical probe.

[0032] Fluid flow through the cryosurgical probe is as follows. High pressure fluid, preferably gaseous argon, and preferably at a pressure of about 3000 psi, is supplied to the assembly through high pressure fitting 47, flows through gas supply line 44, through the cryostat, i.e. heat exchanger 26, through the Joule-Thomson tube assembly 34 and out the Joule-Thomson nozzle 50. The high pressure gas expands within the expansion chamber 42 and cools to cryogenic temperatures. Condensation of the gas is preferably avoided but can be tolerated. After expanding, the gas is at lower pressure and exhausts over the exhaust gas pathway that includes flow over the outside of the coils of the heat exchanger 26. Because it is now cold, it cools the gas flowing inside the coils. This makes cooling more efficient and achieves colder temperatures. After passing through the heat exchanger, the exhaust gas flows through the remainder of the exhaust gas pathway. The exhaust gas is, typically, eventually vented to the atmosphere.

[0033] Prior art warming methods such as exhaust blocking, reverse flow heat transfer, and electrical heating can be employed. The preferred method of warming is to supply high pressure helium gas through the supply line, heat exchanger and Joule-Thomson nozzle. Helium gas heats up when expanded through the gas outlet. Thus, the supply of gas to the probe can be switched from high pressure nitrogen or argon to high pressure helium to effect rapid re-warming of the nozzle. Helium gas heats up when expanded through the gas outlet. Thus, the supply of gas to the probe can be switched from high pressure nitrogen or argon to high pressure helium to effect rapid re-warming of the cryosurgical probe.

[0034] Although the cryosurgical probe of the present invention has been shown as being straight it may be shaped to accommodate varying uses. For example, referring now to FIG. 4, an embodiment is illustrated, generally designated 52, in which a housing extension 53 is curved to make the invention particularly useful, for example, where space limitations exist. This may be useful, for example, if the cryosurgical probe is utilized in a CT device. In addition to its utilization relative to CT guidance, the cryosurgical probe 52 may be used with a variety of guidance tools, such as MRI and ultrasound.

[0035] Referring now to FIG. 5, another embodiment is illustrated, designated generally as 54. In this embodiment, threads are not used. Instead, there is a radial extension 56 on the cylindrical actuator 58 that engages a complimentary groove 60 on the actuator housing 62 so when the positionable assembly is rotated relative to the stationary assembly there is no longitudinal movement. As can be seen in FIG. 6, insulation 64 is located on a selected portion of the cryosurgical shaft assembly 66 so that rotation effects a change in the freeze zone. In this figure the insulation 64 is shown to be about 180 degrees. Obviously, it can be configured as desired for the particular application.

[0036] Although the present invention has been discussed relative to the use of a Joule-Thomson tube assembly in conjunction with a cryostat assembly to provide a delivery system for a cryogenic fluid, it is understood that various other types of cryogenic delivery systems may alternatively be used such as liquid nitrogen.

[0037] Referring now to FIGS. 7 and 8, an embodiment of the present invention is illustrated, designated generally as 70, in which the actuator housing and the cylindrical actuator are reversed. The cryosurgical probe 70 includes an actuator housing assembly (i.e. stationary assembly), designated generally as 72, and an actuator assembly (i.e. positionable assembly), designated generally as 73. The stationary assembly 72 includes an actuator housing 74 having an elongated central opening therethrough and a cryosurgical shaft assembly 76 securely attached to the distal end portion of the actuator housing.

[0038] The actuator assembly 73 includes a rotatable cylindrical actuator 78 having a portion thereof contained within the actuator housing 74. The cylindrical actuator 78 is rotatable relative to the actuator housing 74.

[0039] As in the previous embodiment, a cryostat assembly 80 comprises a cryostat housing 82. The cryostat housing 82 includes a cryostat housing attachment end 84 secured to the rotatable cylindrical actuator 78. A cylindrical insulation layer 86 has a proximal portion securely attached to the rotatable cylindrical actuator 78. A Joule-Thomson tube assembly 88 is securely positioned within the cylindrical actuator. Thus, rotation of the rotatable cylindrical actuator 78 provides desired freezing.

[0040] This embodiment may be modified, as was the previous embodiment, to provide for longitudinal relative movement or only radial motion (i.e. by a groove) so that rotation effects a change in the freeze zone.

[0041] Although the present invention has been discussed above with respect to a cryosurgical probe having with a rigid outer sheath, the cryosurgical probe may be made to be malleable by including at least one malleable segment thereon. Malleable segments are formed of material that permit reshaping and bending to reposition the ablating surface for greater ablation precision. An example of a cryosurgical probe having malleable characteristics is disclosed and claimed in patent application Ser. No. 09/957,337, Pub. No. U.S. 2003/0055415 A1, filed on Sep. 20, 2001 entitled Malleable Cryosurgical Probe, incorporated in its entirety herein by reference.

[0042] One method for providing malleable characteristics includes providing a malleable shaft with a bellows portion. Patent application Ser. No. 10/057,033, Pub. No. U.S. 2003/0055416 A1, filed on Jan. 23, 2002 entitled Cryosurgical Probe With Bellows Shaft, incorporated in its entirety herein by reference, discloses use of a bellows portion for providing the necessary reshaping and bending.

[0043] If the cryosurgical probe is utilized in combination with ultrasound the outer sheath may have an echogenic coating with, for example, a porous microstructure having the ability to trap microscopic air bubbles. This creates thousands of highly efficient ultrasound reflectors on the surface of the sheath.

[0044] Other embodiments and configurations may be devised without departing from the spirit of the invention and the scope of the appended claims. 

1. A cryosurgical probe for providing an adjustable freeze zone, comprising: an actuator housing assembly, comprising: a) an actuator housing having an elongated central opening therethrough, said actuator housing having a proximal end portion and a distal end portion; b) a delivery system for a cryogenic fluid, including a first end secured to said proximal end portion of said actuator housing; and, c) an insulation layer having a proximal portion securely attached to said proximal end portion of said actuator housing; and, an actuator assembly, comprising: a) a rotatable actuator having a portion thereof contained within said actuator housing, said rotatable actuator being rotatable relative to said actuator housing; and, b) a cryosurgical shaft assembly securely attached to said rotatable actuator, said insulation layer extending along an inner surface of said cryosurgical shaft to define insulated portions of said cryosurgical shaft and uninsulated portions, the relative disposition of insulated and uninsulated portions of said cryosurgical shaft assembly defining at least one freeze zone which is adjustable by relative rotation between said rotatable actuator and said actuator housing.
 2. The cryosurgical probe of claim 1, wherein said delivery system comprises: a) a cryostat assembly comprising a cryostat housing, said cryostat housing including a cryostat housing attachment end secured to said proximal end portion of said actuator housing; and, b) a Joule-Thomson tube assembly securely positioned within said actuator housing.
 3. A cryosurgical probe for providing an adjustable freeze zone, comprising: a stationary assembly, comprising: a) an actuator housing having an elongated central opening therethrough, said actuator housing having a proximal end portion and a distal end portion; b) a cryostat assembly comprising a cryostat housing, said cryostat housing including a cryostat housing attachment end secured to said proximal end portion of said actuator housing; c) a stationary cylindrical insulation layer having a proximal portion securely attached to said proximal end portion of said actuator housing; and, d) a Joule-Thomson tube assembly securely positioned within said actuator housing; and, a positionable assembly, comprising: a) a rotatable cylindrical actuator having a portion thereof contained within said actuator housing, said cylindrical actuator being rotatable relative to said actuator housing; and, b) a cryosurgical shaft assembly securely attached to said rotatable cylindrical actuator, wherein rotation of said rotatable cylindrical actuator provides desired freezing.
 4. The cryosurgical probe of claim 3, wherein said rotatable cylindrical actuator is operatively engaged with said actuator housing to provide axial movement therebetween during rotation of said rotatable cylindrical actuator thereby changing the length of said freeze zone.
 5. The cryosurgical probe of claim 3, wherein said rotatable cylindrical actuator is operatively engaged with said actuator housing to provide axial movement therebetween during rotation of said rotatable cylindrical actuator, thereby changing the length of said freeze zone, said rotatable cylindrical actuator being threadably engaged with said actuator housing.
 6. The cryosurgical probe of claim 3, wherein said cryosurgical shaft assembly comprises insulation formed on a selected portion thereon to provide a rotatable freeze zone upon rotation of said rotatable cylindrical actuator.
 7. A cryosurgical probe for providing an adjustable freeze zone, comprising: an actuator housing assembly, comprising: a) an actuator housing having an elongated central opening therethrough, said actuator housing having a proximal end portion and a distal end portion; b) a cryosurgical shaft assembly securely attached to said distal end portion of said actuator housing; an actuator assembly, comprising: a) a rotatable actuator having a portion thereof contained within said actuator housing, said rotatable actuator being rotatable relative to said actuator housing, said rotatable actuator having a proximal end portion and a distal end portion; b) a delivery system for a cryogenic fluid secured to said rotatable actuator; and, c) an insulation layer having a proximal portion securely attached to said rotatable actuator, said insulation layer extending along an inner surface of said cryosurgical shaft to define insulated portions of said cryosurgical shaft and uninsulated portions, the relative disposition of insulated and uninsulated portions of said cryosurgical shaft assembly defining a least one freeze zone which is adjustable by relative rotation between said rotatable actuator and said actuator housing.
 8. The cryosurgical probe of claim 7, wherein said delivery system comprises: a) a cryostat assembly comprising a cryostat housing, said cryostat housing including a cryostat housing attachment end secured to said proximal end portion of said actuator housing; and, b) a Joule-Thomson tube assembly securely positioned within said actuator housing.
 9. A cryosurgical probe for providing an adjustable freeze zone, comprising: a stationary assembly, comprising: a) an actuator housing having an elongated central opening therethrough, said actuator housing having a proximal end portion and a distal end portion; b) a cryosurgical shaft assembly securely attached to said distal end portion of said actuator housing; a positionable assembly, comprising: a) a rotatable cylindrical actuator having a portion thereof contained within said actuator housing, said cylindrical actuator being rotatable relative to said actuator housing; b) a cryostat assembly comprising a cryostat housing, said cryostat housing including a cryostat housing attachment end secured to said rotatable cylindrical actuator; c) a cylindrical insulation layer having a proximal portion securely attached to said rotatable cylindrical actuator; and, d) a Joule-Thomson tube assembly securely positioned within said cylindrical actuator, wherein rotation of said rotatable cylindrical actuator provides desired freezing.
 10. The cryosurgical probe of claim 9, wherein said rotatable cylindrical actuator is operatively engaged with said actuator housing to provide axial movement therebetween during rotation of said rotatable cylindrical actuator thereby changing the length of said freeze zone.
 11. The cryosurgical probe of claim 9, wherein said rotatable cylindrical actuator is operatively engaged with said actuator housing to provide axial movement therebetween during rotation of said rotatable cylindrical actuator, thereby changing the length of said freeze zone, said rotatable cylindrical actuator being threadably engaged with said actuator housing.
 12. The cryosurgical probe of claim 9, wherein said rotatable cylindrical actuator is operatively engaged with said actuator housing to provide axial movement therebetween during rotation of said rotatable cylindrical actuator, thereby changing the length of said freeze zone, said rotatable cylindrical actuator being threadably engaged with said actuator housing.
 13. The cryosurgical probe of claim 9, wherein said cryosurgical shaft assembly comprises insulation formed on a selected portion thereon to provide a rotatable freeze zone upon rotation of said rotatable cylindrical actuator. 